What is a PubSub subscription?
"Subscriptions" are how PubSub keeps an eye on the Internet
for you. When you create a PubSub subscription, you provide a
set of keywords that the Matching Engine can use to identify
items on the Web that you would like to know about. The system
monitors an enormous assortment of sources and whenever an item appears that matches your
criteria, PubSub will immediately capture it for your. You can
view these matched items in an RSS aggregator, by visiting the PubSub
website, or by using our Sidebar.
How do I write in the keywords for a subscription?
In the "Enter your keywords…" box just type in a list
of the words you're interested in. Separate the items by a
space, and enclose exact phrases by quotes. By default the
system will assume that words or phrases in this
list should be connected by an "OR"
relationship. For example, if you enter the following:
dogs "great danes"
your subscription will return any Web pages that contain either the word "dogs", the phrase "great danes", or both. Capitalization doesn't matter.
It's possible to create rules that are much more detailed than this. For more information, see our Subscription Syntax page.
How can I view my results?
You can do this in several ways:
- On the Web: When you have created a new subscription, you'll see a page with a section labeled "What Now?". In this section there is a link that says Bookmark this subscription for later viewing in your browser. Clicking this link will take you to your new subscription's digest page. If you bookmark this page you can return to it anytime to see your results.
- RSS Aggregators:: You can view your subscription results with an online or desktop aggregator (news aggregators are applications that are designed to display links to Web items). To add the subscription to your Yahoo! or BlogLines aggregator, just click one of the buttons under the Read it in your favorite news aggregator heading. To add the feed to any other reader software, you can get the URL you need by right-clicking the appropriate ("RSS" or "Atom") link and clicking "Copy Shortcut". Following the "Add feed" instructions in your aggregator, and then pasting the link where appropriate.
- The PubSub Sidebar: The fastest way to get your results is to see them arriving in real time with the PubSub Sidebar. This is an extension for your Web browser that allows you to see matched items as soon as we find them for you. There are two versions — one for Internet Explorer, and one for Mozilla Firefox. You can download the Sidebar here.
- The PubSub XMPP Server: The Sidebar gets its streaming data from the PubSub XMPP Server. This publically available server uses the XMPP Instant Messaging Protocol to deliver XML-formatted subscription results in real time, and also offers an API that allows the creation/deletion of subscriptions as well as other useful PubSub functionality. If you are an application developer and want to build your own PubSub client software, please read the Tools section of our website. We also maintain an open-source project with some downloadable code samples and a .Net XMPP client library at SourceForge.
What kind of results can I expect from a PubSub subscription?
Unlike a conventional search engine which indexes as many pages as it can and stores static copies of them in a database for later retrieval, the PubSub system tracks sources that are updated frequently, like weblogs, newsgroups, press releases, and airport status reports. Once you have created a PubSub subscription, our matching engine will monitor these dynamic sources for you in real time, checking your subscription criteria against the constantly changing content, and delivering matching items to you as soon as they appear.
Why do I get duplicate results?
Although our duplicate-detection process generally works very
well, nothing is perfect and occasionally an item will
slip through that seems identical to one that has
been published earlier. We feel that we must be careful
not to be too aggressive in eliminating duplicates, since some
users are interested in seeing content that has been
republished with minor modifications. This often happens when bloggers paste
content from other blogs into their own page.
I'm getting a lot of junk along with the results I want. How can I "tighten" my subscription?
It is always possible to fine-tune your subscription to
return better results. For example, a
subscription using just the keyword ford will return items
referring to Harrison Ford, Gerald Ford, or the Ford Modeling
Agency, as well as postings about Ford automobiles. To filter
the results a bit more, you can enclose phrases in quotes,
like "harrison ford", or you can use Boolean AND, OR,
and NOT operators, e.g.:
ford AND ( NOT ( harrison OR gerald
OR agency ) ). To learn more, see our Boolean Help page.
Once a subscription is made, how long do I have to wait until I get my first match? This depends on the particular information you're looking for. You will see matches as soon as any of your subscription terms appear in any of our sources. This might be a matter of seconds or days.
Can I get subscriptions only in a particular language?
No. When you make a subscription, the Matching Engine will begin examining source pages for matches, regardless of what language the pages are written in, and will return links to any pages that match your criteria. We do not yet support language filtering, but may in the future once we are confident that it is accurate.
How often are feeds updated? In most cases, you will see posts just minutes, or even seconds, after they're published. The PubSub matching engine works very quickly. The method of delivery you have chosen for your subscriptions will also be a determining factor. Tools such as the PubSub Sidebar and Gush use XMPP Instant Messaging protocol in order to push results to the user as they are received. RSS aggregators poll our system at periodic intervals and therefore will lag behind the XMPP delivery.
Why should I get a PubSub account?
By creating a PubSub account you will gain the ability to:
- Manage all account subscriptions in a central location
- Edit subscription queries
- Access subscriptions through tools such as the PubSub Sidebar and Gush